Unit ventilator



y 1969 n. R. SCHUSTER ETAL 3,443,506-

UNIT VENTILATOR Filed April 17', 19 67 FIE-LE 3 R a SEN mUU 0 W m a we... sPr R NA m WW wn u Y B F1B-B 75 7/0.

Int. Cl. F24f 3/06 US. CI. 98-39 10 Claims ABSTRACT OF THE DISCLOSURE A unit ventilator having a fan subassembly comprised of a sheet metal deck plate and depending blower housings. Sheet metal end plates depend from the deck plate for supporting the bearings which carry the radial loads imposed by the fan shaft. The fan shaft runs through all of the centrifugal fans, and is connected to a motor located outside the air stream. Preferably the fan subassembly is fabricated separately from the conditioner housing, and is installed by sliding same rearwardly into the housing on ledges formed by the end walls of the air stream passage. Servicing of the fan subassembly can be accomplished by removal of the entire subassembly.

Background This invention relates to unit ventilators which are used for example in school rooms to supply the rooms with hot or cold air.

Such ventilators sometimes comprise an upright unit ventilator casing having a motor driven fan means arranged therein to blow air upwardly across a heat exchange coil which is connected With a source of hot and/ or cold water. Supply air for the ventilator is usually taken through two separate air inlet openings in the lower portions of the front and rear walls, the rear opening being a fresh air opening, and the front opening being a return air opening.

A variable ratio of the return air to fresh air is accomplished by means of a roll damper swingably suspended beneath the fan means to swing across the two separate inlet openings. The roll damper is usually con trolled by a thermostatically-operated motor connected with the damper pivot means. To minimize the load on this motor there is usually provided a spring which counterbalances the shifting weight of the damper as it swings through its arc between the two limiting positions.

Objects of the invention One object of the present invention is to provide a unit ventilator having a fan subassembly which has structural strength to resist twisting and deflection of its sheet metal parts, which can be formed as a complete subassembly separate from the ventilator housing, which can be removed from the housing for easy field service and maintenance, which is precision-aligned prior to installation to minimize generation of motor and blower noise and vibration, which is ambidextrous for left or right hand drive, which locates the drive motor out of the air stream and foreign matter entrained therein, and which eliminates air flow restrictions caused when the motor is located in or adjacent the fan inlets.

A further object is to provide a unit ventilator having a damper counterbalancing spring which substantially balances the weight of the damper in all damper positions, which allows the damper operator to accurately adjust the damper without undue hysteresis, which allows the damper to fully close in either limiting position, which enables the damper operator to have a relatively low and constant torque over the entire damper stroke, and which functions without interference from the fan shaft extending through the unit ventilator air stream passage.

nited States Patent 3,443,506 Patented May 13, 1969 The drawings FIG. 1 is a sectional view taken through one embodiment of the invention on line 11 in FIG. 2.

FIG. 2 is a sectional view taken on line 22 in FIG. 1.

FIG. 3 is a front elevational view of a fan assembly used in the FIG. 1 embodiment but taken on a reduced scale.

FIG. 4 is a sectional view taken on line 44 in FIG. 3.

FIG. 5 is an exploded greatly reduced side elevational view showing diagrammatically the relationship between the fan assembly and support mechanism used in the FIG. 1 embodiment.

FIG. 6 is an exploded reduced perspective view of certain casing components used in the FIG. 1 embodiment.

General arrangement The illustrated unit ventilator comprises an upright casing 30 having a fresh air filter 94 in its lower rear portion and a return air filter 92 in its front lower portion, suitable inlet openings being formed in the casing rear and front walls to supply the filters with inlet air. Positioned above the filters 92 and 94 is a roll damper 98 having two sector arms 100 carried on aligned stub shafts 102 which go through the end walls of the air passage structure. A damper operator (not shown) causes the damper to move across the two air filters 92 and 94 to thus vary the relative proportions of fresh and return air.

The air passing upwardly across the damper is drawn into a plurality of, for example three, centrifugal fan wheels 27 located in scroll type fan housings 26, said fan wheels being powered by an electric drive motor 66 located outside the air stream (see FIG. 2). Air discharged from the centrifugal fans is passed through a finned heat exchange coil 132 (plate type fins) or therearound, depending on the position of the pivotally mounted bypass damper 130. The bypass and/or treated air is discharged from the ventilator through a grilled outlet 134. A fixed bafile 136 cooperates with damper in keeping the by pass and treated air streams separated while in the ventilator casing.

In some cases the bypass damper 130 can be replaced by a thermostatically-controlled modulating valve (or a series of separate valves) located in the liquid line which circulates hot or cold fluid through coil 132. Such a valve, not shown, would vary the amount of liquid flowing or the number of coil sections supplied with liquid. In this way the tempering effect of the coil is varied without the damper 130.

Fan assembly Referring to FIG. 3, there is shown a fan assembly comprising a generally horizontal deck plate 10 formed of sheet metal and having two depending integrally formed end plates 12 and 14 which are provided with feet-forming flanges 16 and 18. In the illustrated arrangement each flange 16 or 18 mounts a pillow block bearing 20 which rotatably supports the end portions 22 of an elongated fan shaft 24. If desired flange-mounted bearings can be used instead of the illustrated foot-mounted type; in that event the bearing flanges would seat against the respective end plate 12 or 14. Shaft 24 extends through three scroll type blower housings 26 suspended from the deck plate 10. To suspend the individual blower housings the deck plate is provided with rectangular openings dimensioned according to the discharge area of each housing 26; depending flanges 28 are formed along opposite edges of each opening to receive screws going through the sidewalls of each blower housing.

Rigidity is given to the fan deck by longitudinal flanges 17 and 19 depending from opposite edges of plate 10, and by flanges 21 and 23 extending from opposite edges of end walls 12 and 14. Two gussets 25 are adhered, as by screws, rivets, bolts, welding, etc., to the reinforcement flanges at their adjoining edges near the front corners between deck plate and end plates 12 and 14. In the drawing numeral 7 identifies certain gusset attachment screws which may be used. Deck plate 10, end walls 12 and 14, and the reinforcement flanges are preferably formed as an integral one piece sheet metal member, which may be of relatively light gauge, as for example 14 gauge galvanized steel. In spite of the light gauge the unit possesses very good rigidity and twist resistance due to the manner of formation with reinforcement flanges and gussets.

Positioned within each scroll housing 26 is a centrifugal fan wheel 27 (FIG. 1) of the double inlet type, each wheel being carried on and locked to the drive shaft 24. Assembly of the shaft-fan components in the fan deck may be accomplished by positioning the fan wheels loosely in housings 26, moving shaft 24 through the hubs of the wheels without locking the wheels in place, extending the ends of the shaft through oversize openings in end plates 12 and 14 by a tilting-sliding action of the shaft, and installing the bearings 20 on the projecting shaft ends. Housings 26 may then be screwed to deck flanges 28, and fan wheels 27 locked at the correct locations on shaft 24. The number of fan-housing units may of course vary (two, three or four being the usual number).

Ventilator casing construction The FIG. 3 fan assembly may be positioned within a unit ventilator casing 30 (FIG. 1) having a rear wall 32 and a removable front wall 34. Extending across the upper rear corner of the casing is a reinforcement frame member 36. Additional reinforcement frame members 38 and 40 extend across the upper front and lower front corners of the casing to provide structural rigidity thereto. The width of the ventilator casing (arrow 40 direction in FIG. 2) may be on the order of 60 to 100 inches, the height about 30 inches, and the front to rear depth about inches.

Rear wall 32 is provided with a forwardly extending flange 76 which is welded to a subjacent flange formed on the inner plate-like wall 74, said wall 74 having a rearwardly turned portion 77 which is flanged at 79 to form a welded joint with an intermediate portion of wall 32. The space defined by walls 32, 76, 74 and 77 constitutes a transverse box section 81 for rigidifying the ventilator casing, as well as a pipe raceway for containing the water piping used to supply hot and/or cold water to the heat exchange coils in the various ventilators of the system.

Box section 81 extends across the rear central portion of the ventilator casing, the spaces therebeyond leaving two full depth end compartments, each about twelve inches wide, for containment of water valves, controls, and drive motor, etc. Two rigidifying upright partitions 42 extend forwardly from the ends of the box section to the front of the casing, the central space between these forwardly extending partitions constituting the air passageway through the ventilator casing. Only one of the partitions is visible in FIG. 2, but both are mirror images of one another. Hence a description of one will suffice for the other.

Each partition 42 comprises three vertical elements or panels 44, 46 and 48. Panel 44 is part of a U-shaped member 59 which defines the rear and side walls of the aforementioned end compartment. Wall element 44 comprises a vertical sheet metal section having a full length flange 50 at its lower edge (FIG. 2), a full length contoured flange 52 at its front edge (FIG. 1), and a full length flange 54 at its upper edge. Panel 44 is formed integrally with a full height sheet metal Wall section 56 which defines the rear portion of an end compartment. Section 56 is turned forwardly at its left edge to define an end wall 58 for the compartment. Thus panel sections 44, 56 and 58 are part of a single end compartment member 59 having a U-shaped cross section in vertical plan,

As shown in FIG. 2, the upper and lower edges of panel section 58 are flanged at 60 and 62 for reinforcement purposes. Flange 60 also forms a support surface for a motor-mount plate 64 having its left end turned down at 65 for securement to panel section 44. The motor, designated by numeral 66, is provided with a drive shaft 68 which connects with one of the shaft extensions 22 by means of a conventional flexible coupling 70.

Aforementioned panel 46 extends upwardly from panel 44 and is provided with three flanges 72, and 77a, said flange 72 abutting against flange 54 and being secured thereto, as by Welding. Aforementioned panel 48 is provided with a full length flange 80 at its front edge, a full length flange 82 at its upper edge, and a full length flange 84 at its rear edge. Its lower edge 86 is not flanged, but it does extend downwardly alongside the end plate 12 to be secured thereagainst by two nut-bolt assemblies 88 going through intersecting slots in the plate and panel. Flange 84 on panel 48 abuts against wall 74 of box section 81 and is permanently secured thereto as by Welding.

The ventilator casing is formed primarily by the three full width frame members 36, 38 and 40, the two end compartment members 59, the transverse box member 81, the two small forwardly extending panels 46, and the two large forwardly extending panels 48. Panels 44, 46 and 48 are in the same vertical plane to form an upright partition 42 located adjacent each end of box member 81.

Installation of the fan assembly It will be seen that the three panels 44, 46 and 48 are secured together along their meeting flanges to form a partition 42 having a cut-out 90 extending rearwardly from the partition front edge; this is shown best in FIG. 5. The cut-out is designed to accommodate the projecting end portions of shaft 24 during installation of the FIG. 3 fan deck into the FIG. 1 ventilator casing. Thus, assuming the casing front wall 34 is removed from or not yet installed on the casing, the cut-out 90 in each vertical partition 42 will form a clear space to receive the projecting end 22 of the fan shaft when the FIG. 3 fan assembly is slid as a unit into the ventilator casing. During the assembly process the flexible coupling 70 is disassociated from the shaft portion 22 of the motor shaft 68. Final connection of the coupling between the motor shaft and fan shaft is accomplished by set screws (not shown) after the FIG. 3 fan unit has been installed.

Retention of the fan unit is accomplished by two nutbolt assemblies 88 going through each panel 48 and adjacent end plate 12 or 14, and a single nut-bolt assembly 91 going through each flange 16 or 18 and the subjacent flange 54. The nut-bolt assemblies 21a which mount each pillow block bearing 20 on the respective flange 16 or 18 do not have any connections with flange 54. Each flange 54 is provided with oversize openings to accommodate the heads of the bolts in the bolt-nut assemblies 21.

Roll damper construction Room air is admitted to the unit ventilator through a rectangular filter 92 suitably positioned in the air stream passage defined between partitions 42. The return air supply is taken through an inlet opening extending across the lower front portion of the casing between partitions 42; this opening is designated generally by numeral 95. Fresh air is admitted to the casing through a filter 94 which registers with an elongated fresh air inlet opening 96 extending across the lower rear portion of the ventilator casing. The proportion of fresh air to room air is regulated by an arcuate roll damper 98 carried on two sheet metal sector arms 100 located closely adjacent respective ones of the two panels 44. Stub shafts 102 extend from each sector arm through hearings in each panel 44 to swingably suspend the roll damper. The damper may be moved from its illustrated 100% return air position to a nonillustrated 100% fresh air position in which its front edge 104 engages a fixed bafile 106. In its illustrated p h tion the damper has its front edge 104 spaced from the fixed baflle 106 to allow room air to pass through the intervening space to the centrifugal fan housings 26. The dampers rear edge 108 is engaged with a fixed baflle 110 to prevent admission of fresh air to the fan housings. Any undesired air bypass is prevented by a longitudinal partition 112 having an upper felt seal 114 rubbing against damper 98 and a lower felt seal 116 against filter 92.

Damper counterbalancing The damper 98 may be moved counterclockwise from its illustrated position in a graduated manner to progressively increase the admission of fresh air and progressively restrict with admission of return air. The power for this purpose is conventionally derived from a thermostaticallyoperated motor connected with one of the stub shafts 102. To minimize the load on this motor it is conventional to provide a spring mechanism for counterbalancing the weight of the roll damper in its various partitions. Conventionally this spring takes the form of a tension spring acting generally upwardly in a vertical direction and swingable across the shaft 102 axis to provide a damper lifting force compensating for the weight of the damper in its different positions. In the present unit the single drive shaft for the fan wheels extends entirely across the air stream passageway, and thus would interfere with the usual vertically arranged counterbalancing spring. Therefore the illustrated unit utilizes a novel counterbalancing spring 118 which is located to clear the fan shaft in all spring positions.

The illustrated spring 118 is connected with a fixed anchorage 120 adjacent the rear wall of the casing and a second pin-like anchorage 122 on the roll damper. The spring includes a sheet metal link 124 having a U-shaped offset portion for allowing the spring to clear the fan shaft 24 when the damper is in its 100% fresh air position. Anchorage 122 is mounted on a plate-like arm 126 which is bolted flatwise against the adjacent sector plate 100, arm 126 in effect constituting part of the sector arm and associated damper.

It will be seen from FIG. 1 that the weight of damper 98 tends to displace the damper from its illustrated position forwardly (counterclockwise) to an intermediate position in which seal 114 engages the mid-line of the damper. However spring 118 acts against the gravitational force to hold the damper in its illustrated position. Preferably the spring is chosen and adjusted so that it substantially balances the damper weight in the illustrated position; this will allow the damper motor to operate the damper counterclockwise with a lesser torque loading than would otherwise be possible, thus enabling use of a relatively low cost motor. As the damper motor moves the damper forwardly to the 50% return air-50% fresh air position the spring anchorage 122 takes a position 122a in which the spring has a horizontal line of action extending through the swing axis defined by stub shafts 102. In this position the damper weight presents minimum load on the damper motor since the arcuate damper 98 is at its intermediate or lowest point in the swing. Spring 118 in this position exerts substantially no counterbalancing action on the damper since it exerts no vertical force component thereon.

In its 100% fresh air position spring anchorage 122 assumes position 12212, the spring line of action at this time extending forwardly and upwardly to cause the spring to exert an upward lifting force proportioned to the displacement of the damper from its gravity-centered intermediate position. The general effect of the spring arrangement is to provide a counterbalancing effect which varies in accordance with the displacement of the roll damper from the natural position that the damper would take in the absence of any force thereon. This assures that the damper-spring assembly will present a minimum and substantially constant load on the actuator motor, thus allowing the torque requirements of the motor to be kept constant and small.

Features of the invention One principal feature of the invention is the employment of partitions 42 having cut-outs in their forward edges for accommodating the ends of shaft 24 during installation and removal of the FIG. 3 fan assembly. The formation of each partition 42 as a three panel structure, reinforced with peripheral flanges, enters into this aspect of the development, since it enables the partitions to be formed with the cut-outs 90 without sacrifice in casing rigidity or service life.

The construction of the fan deck 10 with integral reinforcement flanges and strengthening gussets is important in enabling the fan deck to be economically formed as a subassembly apart from the casing, while having the assurance that the fan deck will not warp, twist or otherwise be deformed prior to or during initial installation of the fan into or removal from the casing for service, etc.

A final feature of some importance is the construction and location of the damper counterbalancing spring 118 which permits the fan subassembly to be installed in the casing or removed without interference from the spring.

It will be understood that some variation in construction and arrangement in one or more of the components may be resorted to without departing from the spirit of the invention as comprehended by the attached claims.

It is claimed:

1. A unit ventilator comprising a casing having a rear Wall, a removable front wall, and two laterally spaced upright partitions extending between the front and rear walls to define a central air stream space and at least one end compartment; a removable fan assembly positioned behind the casing front wall for withdrawal through the casing front, said assembly comprising a generally horizontal deck plate extending between said partitions to separate the air stream space into a lower air inlet chamber and an upper air outlet chamber, end plates carried by and depending from said deck plates in the general planes of the upright partitions, at least two centrifugal fan housings depending from the fan deck for discharging air into the space thereabove, a bearing carried by each end plate, a single fan shaft extending through the fan housings with its opposite ends supported in the two bearings, and centrifugal fan wheels arranged on the shaft within respective ones of the housings; means carried by each upright partition for collectively supporting said removable fan assembly; said fan shaft having at least one of its ends projecting into an end compartment for operable connection with a drive motor disposed therein; said shaft having a length greater than the spacing between the upright partitions; said partitions having cutouts extending rearwardly from their front edges to accommodate the projecting ends of the fan shaft during installation and removal of the fan assembly.

2. The unit ventilator of claim 1 and further comprising a pipe raceway extending across the rear central portion of the casing and defining a hollow rigid box section; the upright partitions being located at the ends of said box section; each upright partition comprising a first lower peripherally flanged panel extending the full depth of the ventilator casing, a second upstanding flanged panel extending upwardly from the rear portion of the lower panel to the box section, and a third upper peripherally flanged panel extending forwardly from the box section in spaced relation to the first panel to define the aforementioned cut-out.

3. The unit ventilator of claim 2 wherein the upper edge of each lower panel is flanged to form a generally horiz-ontally extending ledge; each of the aforementioned deck end plates being flanged at its lower edge to form an elongated foot surface restable on the respective ledge.

4. The unit ventilator of claim 3 wherein the fan deck is secured to the upright partitions by fasteners going through the ledge-forming flanges and foot-forming flanges.

5. The unit ventilator of claim 1 wherein the deck plate and end plates are formed as a one piece member with integral reinforcement flanges extending along their front and rear edges.

6. The unit ventilator of claim 5 wherein gussets are adhered to adjacent face areas of the reinforcement flanges at the front corners between the deck plate and each end plate.

7. The unit ventilator of claim 1 and further comprising means forming a fresh air inlet opening adjacent the lower portion of the rear wall; means forming a return air inlet opening adjacent the lower portion of the front wall; a roll damper swingably suspended from the twoupright partitions in the space below the fan housings to apportion the air fiow from the two inlet openings; tension spring means trained between a first fixed anchorage adjacent the casing rear wall and a second anchorage on the roll damper to urge the damper rearwardly toward the 100% return air position When the damper is in a range of locations between the 50% return air position and the 100% return air position; said damper being movable from its 100% return air position in a downward arc to the 50% return air position, and then in an upward arc to the 100% fresh air position; the two anchorages being so located that the line of action of the spring passes through the damper swing axis at about the 50% return air position; said spring operating to urge the damper toward the 100% fresh air position when said damper is in a range of locations between the 50% fresh air position and the 100% fresh air position.

8. The unit ventilator of claim 7 wherein the spring takes a forwardly declining attitude in the 100% return air position, a horizontal attitude in the 50% return air position, and a forwardly inclining attitude in the 100% fresh air position.

9. A unit ventilator comprising an upright casing having a rear wall, a removable front wall, and two laterally spaced upright partitions extending between the front and rear walls to define a central air stream space and at least one end compartment; a deck plate extending between the partitions to separate the air stream space into a lower air inlet chamber and an upper air outlet chamber; at least two fan housings carried by the deck for discharging air into the space above the deck; a single fan shaft extending through the fan housings and beyond the partitions; fan

wheel-s arranged on the shaft within respective ones of the housings; a motor disposed in said end compartment in operable driving connection with the fan shaft; means forming a fresh air inlet opening adjacent the lower portion of the rear wall; means forming a return air inlet opening adjacent the lower portion of the front wall; a roll damper swingably suspended from the two upright partitions in the space below the fan housings to apportion the air flow from the two inlet openings; tension spring means trained between a first fixed anchorage adjacent the casing rear wall and a second anchorage on the roll damper to urge the damper rearwardly toward the 100% return air position when the damper is in a range of locations between the return air position and the return air position; said damper being movable from its 100% return air position in a downward arc to the 50% return air position, and then in an upward arc to the 100% fresh air position; the two anchorages being so located that the line of action of the spring passes through the damper swing axis at about the 50% return air position; said spring operating to urge the damper toward the 100% fresh air position when said damper is in a range of locations between the 50% fresh air position and the 100% fresh air position.

10. The unit ventilator of claim 9 wherein the spring takes a forwardly declining attitude in the 100% return air position, a horizontal attitude in the 50% return air position, and a forwardly inclining attitude in the 100% fresh air position.

References Cited UNITED STATES PATENTS 1,816,217 7/1931 Harriett 98-39 XR 1,950,768 3/1934 Anderson 98-38 2,043,561 6/1936 Sims 98-39 2,229,304 l/l941 Shurtletf -103 XR 2,909,043 10/1959 Baker et a1. 16516 XR 3,262,491 7/1966 Selhost 165-48 XR FRED C. MATTERN, JR., Primary Examiner.

MANUEL ANTONAKAS, Assistant Examiner.

U.S. Cl. X.R. 165-16, 48 

